Patents by Inventor Ken Morito

Ken Morito has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 8736956
    Abstract: An optical amplification control apparatus is formed from a semiconductor optical amplifier, a temperature adjustment unit adjusting the temperature of the semiconductor optical amplifier, and an optical gain control unit adjusting the temperature of the semiconductor optical amplifier by controlling the temperature adjustment unit, and varying an optical gain of the semiconductor optical amplifier. Thus, a pattern effect is suppressed even if the output light intensity (the intensity of amplified light) is increased.
    Type: Grant
    Filed: March 15, 2011
    Date of Patent: May 27, 2014
    Assignee: Fujitsu Limited
    Inventors: Shinsuke Tanaka, Ken Morito
  • Patent number: 8073033
    Abstract: Objects are achieved by an optical semiconductor device comprising: a structure 61 including a substrate 50, a diffraction grating 52a, an active layer 54 and a refractive index control layer 60; and an laser element 100 including an electrode 92a for the active layer, an electrode 92b for the refractive index control layer and an electrode 92c for switching, wherein a pre-bias current is previously supplied from the electrode 92a for the active layer to the active layer 54 in a state where a switching current is not supplied from the electrode 92c for switching to the active layer 54, and then while a current Idrive for activation is supplied from the electrode 92a for the active layer to the active layer 54, the laser element 100 is turned on by supplying the switching current Isw from the electrode 92c for switching to a part of the active layer 54, as well as turning off the laser element 100 by halting the supply of the switching current Isw.
    Type: Grant
    Filed: November 12, 2009
    Date of Patent: December 6, 2011
    Assignee: Fujitsu Limited
    Inventors: Akinori Hayakawa, Ken Morito
  • Publication number: 20110164310
    Abstract: An optical amplification control apparatus is formed from a semiconductor optical amplifier, a temperature adjustment unit adjusting the temperature of the semiconductor optical amplifier, and an optical gain control unit adjusting the temperature of the semiconductor optical amplifier by controlling the temperature adjustment unit, and varying an optical gain of the semiconductor optical amplifier. Thus, a pattern effect is suppressed even if the output light intensity (the intensity of amplified light) is increased.
    Type: Application
    Filed: March 15, 2011
    Publication date: July 7, 2011
    Applicant: FUJITSU LIMITED
    Inventors: Shinsuke TANAKA, Ken MORITO
  • Patent number: 7859745
    Abstract: A polarization-independent SOA having an InP substrate used as a semiconductor substrate, and an active layer taking an MQW structure formed of a barrier layer made of GaInAs with tensile strain applied thereto and a well layer made of GaInNAs with no strain applied thereto alternately laminated in a plurality of layers, here, four layers of the well layer and five layers of the barrier layer are alternately laminated, is proposed.
    Type: Grant
    Filed: April 30, 2008
    Date of Patent: December 28, 2010
    Assignee: Fujitsu Limited
    Inventors: Shinsuke Tanaka, Ken Morito, Susumu Yamazaki
  • Patent number: 7859746
    Abstract: A polarization-independent SOA is provided which uses an InP substrate (11) as a semiconductor substrate and uses GaInNAs having introduced tensile strain as an active layer (14). With this configuration, the polarization independence is achieved by introducing the tensile strain, and high saturation optical output power is realized by reducing the film thickness of the active layer (14) as well as the gain peak wavelength is increased by reducing the band gap of the active layer (14) through use of GaInNAs made by adding nitrogen (N) to GaInAs as a material of the active layer (14) so as to achieve high gain especially in C-band and L-band even when band filling exits at the time of injecting a high current into the active layer (14).
    Type: Grant
    Filed: August 14, 2008
    Date of Patent: December 28, 2010
    Assignee: Fujitsu Limited
    Inventors: Ken Morito, Susumu Yamazaki, Shinsuke Tanaka
  • Patent number: 7829880
    Abstract: A quantum dot semiconductor device includes an active layer having a plurality of quantum dot layers each including a composite quantum dot formed by stacking a plurality of quantum dots and a side barrier layer formed in contact with a side face of the composite quantum dot. The stack number of the quantum dots and the magnitude of strain of the side barrier layer from which each of the quantum dot layers is formed are set so that a gain spectrum of the active layer has a flat gain bandwidth corresponding to a shift amount of the gain spectrum within a desired operation temperature range.
    Type: Grant
    Filed: March 13, 2008
    Date of Patent: November 9, 2010
    Assignees: Fujitsu Limited, The University of Tokyo
    Inventors: Hiroji Ebe, Kenichi Kawaguchi, Ken Morito, Yasuhiko Arakawa
  • Publication number: 20100061414
    Abstract: Objects are achieved by an optical semiconductor device comprising: a structure 61 including a substrate 50, a diffraction grating 52a, an active layer 54 and a refractive index control layer 60; and an laser element 100 including an electrode 92a for the active layer, an electrode 92b for the refractive index control layer and an electrode 92c for switching, wherein a pre-bias current is previously supplied from the electrode 92a for the active layer to the active layer 54 in a state where a switching current is not supplied from the electrode 92c for switching to the active layer 54, and then while a current Idrive for activation is supplied from the electrode 92a for the active layer to the active layer 54, the laser element 100 is turned on by supplying the switching current Isw from the electrode 92c for switching to a part of the active layer 54, as well as turning off the laser element 100 by halting the supply of the switching current Isw.
    Type: Application
    Filed: November 12, 2009
    Publication date: March 11, 2010
    Applicant: FUJITSU LIMITED
    Inventors: Akinori Hayakawa, Ken Morito
  • Patent number: 7633984
    Abstract: Objects are achieved by an optical semiconductor device comprising: a structure 61 including a substrate 50, a diffraction grating 52a, an active layer 54 and a refractive index control layer 60; and an laser element 100 including an electrode 92a for the active layer, an electrode 92b for the refractive index control layer and an electrode 92c for switching, wherein a pre-bias current is previously supplied from the electrode 92a for the active layer to the active layer 54 in a state where a switching current is not supplied from the electrode 92c for switching to the active layer 54, and then while a current Idrive for activation is supplied from the electrode 92a for the active layer to the active layer 54, the laser element 100 is turned on by supplying the switching current Isw from the electrode 92c for switching to a part of the active layer 54, as well as turning off the laser element 100 by halting the supply of the switching current Isw.
    Type: Grant
    Filed: October 17, 2005
    Date of Patent: December 15, 2009
    Assignee: Fujitsu Limited
    Inventors: Akinori Hayakawa, Ken Morito
  • Patent number: 7542201
    Abstract: A semiconductor optical amplification device is disclosed that has a gain spectrum of a wide bandwidth. The semiconductor optical amplification device includes an InP substrate and an active layer on the InP substrate. The active layer has a quantum well structure formed by alternately stacking a barrier layer and a well layer, the barrier layer is formed from a tensile-strained InGaAs film, and the well layer is formed from a compressively-strained InGaAs film.
    Type: Grant
    Filed: February 24, 2006
    Date of Patent: June 2, 2009
    Assignee: Fujitsu Limited
    Inventors: Shinsuke Tanaka, Ken Morito
  • Patent number: 7539378
    Abstract: In order to make it possible to suppress the influence of reflected light on a connection interface easily and with certainty, an optical waveguide device includes a first optical waveguide (1), a second optical waveguide (2) formed from a material or in a structure different from that of the first optical waveguide (1) and connected to the first optical waveguide (1), and a 1×1 multimode interference waveguide (3) formed by increasing the widths of the first optical waveguide (1) and the second optical waveguide (2) in the proximity of a connection interface between the first optical waveguide (1) and the second optical waveguide (2).
    Type: Grant
    Filed: July 17, 2007
    Date of Patent: May 26, 2009
    Assignee: Fujitsu Limited
    Inventors: Kazumasa Takabayashi, Ken Morito
  • Publication number: 20090122393
    Abstract: A polarization-independent SOA is provided which uses an InP substrate (11) as a semiconductor substrate and uses GaInNAs having introduced tensile strain as an active layer (14). With this configuration, the polarization independence is achieved by introducing the tensile strain, and high saturation optical output power is realized by reducing the film thickness of the active layer (14) as well as the gain peak wavelength is increased by reducing the band gap of the active layer (14) through use of GaInNAs made by adding nitrogen (N) to GaInAs as a material of the active layer (14) so as to achieve high gain especially in C-band and L-band even when band filling exits at the time of injecting a high current into the active layer (14).
    Type: Application
    Filed: August 14, 2008
    Publication date: May 14, 2009
    Applicant: FUJITSU LIMITED
    Inventors: Ken MORITO, Susumu YAMAZAKI, Shinsuke TANAKA
  • Patent number: 7508849
    Abstract: A semiconductor optical amplifier, an acousto-optic tunable filter, a phase shifter, a lens, and an internal etalon are arranged in a resonator. Outside the resonator, two lenses, two beam splitters, two photo-detectors, and an external etalon are arranged. The internal etalon is a quartz etalon and the external etalon is a crystal etalon. Therefore, the rate of change in transmission peak wavelength of the internal etalon to a temperature change is greater than that of the external etalon.
    Type: Grant
    Filed: December 27, 2004
    Date of Patent: March 24, 2009
    Assignee: Fujitsu Limited
    Inventors: Shinsuke Tanaka, Ken Morito
  • Publication number: 20080308788
    Abstract: A quantum dot semiconductor device includes an active layer having a plurality of quantum dot layers each including a composite quantum dot formed by stacking a plurality of quantum dots and a side barrier layer formed in contact with a side face of the composite quantum dot. The stack number of the quantum dots and the magnitude of strain of the side barrier layer from which each of the quantum dot layers is formed are set so that a gain spectrum of the active layer has a flat gain bandwidth corresponding to a shift amount of the gain spectrum within a desired operation temperature range.
    Type: Application
    Filed: March 13, 2008
    Publication date: December 18, 2008
    Applicants: FUJITSU LIMITED, THE UNIVERSITY OF TOKYO
    Inventors: Hiroji EBE, Kenichi KAWAGUCHI, Ken MORITO, Yasuhiko ARAKAWA
  • Publication number: 20080310012
    Abstract: A polarization-independent SOA having an InP substrate used as a semiconductor substrate, and an active layer taking an MQW structure formed of a barrier layer made of GaInAs with tensile strain applied thereto and a well layer made of GaInNAs with no strain applied thereto alternately laminated in a plurality of layers, here, four layers of the well layer and five layers of the barrier layer are alternately laminated, is proposed.
    Type: Application
    Filed: April 30, 2008
    Publication date: December 18, 2008
    Applicant: FUJITSU LIMITED
    Inventors: Shinsuke TANAKA, Ken MORITO, Susumu YAMAZAKI
  • Publication number: 20080199128
    Abstract: Aiming at realizing a semiconductor integrated optical element comprising a single semiconductor substrate, and first and second optical waveguides differed in the equivalent refractive index from each other on the semiconductor substrate, allowing light signal to propagate from the first optical waveguide to the second optical waveguide, in which the first and second optical waveguides are provided side-by-side on the semiconductor substrate to form a directional coupler allowing optical coupling between the first and second optical waveguides, and a first-guiding-mode optical signal in the first optical waveguide is output after being converted into a second-guiding-mode optical signal in second optical waveguide, which makes possible to suppress generation of reflection loss and emission loss in optical coupling, and obtain extremely desirable optical coupling characteristics, without causing reflection of optical signal, between different types of optical waveguides differed from each other in the equival
    Type: Application
    Filed: February 14, 2008
    Publication date: August 21, 2008
    Applicant: FUJITSU LIMITED
    Inventors: Shinsuke Tanaka, Ken Morito
  • Patent number: 7295366
    Abstract: An optical integrated device includes a plurality of input optical waveguides connected respectively to a plurality of input ports provided on one end face of the optical integrated device, a single output optical waveguide connected to an output port, an optical coupler for optically coupling signal lights propagated along the plural input optical waveguides to the single output optical waveguide, and a semiconductor optical amplifier gate array formed from a plurality of semiconductor optical amplifiers provided on the input optical waveguides, respectively, and each having an electrode on the surface thereof. The optical integrated device further includes a plurality of signal lines formed on the surface of the optical integrated device in such a manner as to extend from the electrodes to an end face of the optical integrated device on which none of the input ports and the output port is provided.
    Type: Grant
    Filed: June 21, 2006
    Date of Patent: November 13, 2007
    Assignee: Fujitsu Limited
    Inventors: Shinsuke Tanaka, Ken Morito, Haruhiko Kuwatsuka
  • Publication number: 20070258681
    Abstract: In order to make it possible to suppress the influence of reflected light on a connection interface easily and with certainty, an optical waveguide device includes a first optical waveguide (1), a second optical waveguide (2) formed from a material or in a structure different from that of the first optical waveguide (1) and connected to the first optical waveguide (1), and a 1×1 multimode interference waveguide (3) formed by increasing the widths of the first optical waveguide (1) and the second optical waveguide (2) in the proximity of a connection interface between the first optical waveguide (1) and the second optical waveguide (2).
    Type: Application
    Filed: July 17, 2007
    Publication date: November 8, 2007
    Applicant: FUJITSU LIMITED
    Inventors: Kazumasa Takabayashi, Ken Morito
  • Publication number: 20070216996
    Abstract: An optical integrated device includes a plurality of input optical waveguides connected respectively to a plurality of input ports provided on one end face of the optical integrated device, a single output optical waveguide connected to an output port, an optical coupler for optically coupling signal lights propagated along the plural input optical waveguides to the single output optical waveguide, and a semiconductor optical amplifier gate array formed from a plurality of semiconductor optical amplifiers provided on the input optical waveguides, respectively, and each having an electrode on the surface thereof. The optical integrated device further includes a plurality of signal lines formed on the surface of the optical integrated device in such a manner as to extend from the electrodes to an end face of the optical integrated device on which none of the input ports and the output port is provided.
    Type: Application
    Filed: June 21, 2006
    Publication date: September 20, 2007
    Applicant: FUJITSU LIMITED
    Inventors: Shinsuke Tanaka, Ken Morito, Haruhiko Kuwatsuka
  • Publication number: 20070047068
    Abstract: A semiconductor optical amplification device is disclosed that has a gain spectrum of a wide bandwidth. The semiconductor optical amplification device includes an InP substrate and an active layer on the InP substrate. The active layer has a quantum well structure formed by alternately stacking a barrier layer and a well layer, the barrier layer is formed from a tensile-strained InGaAs film, and the well layer is formed from a compressively-strained InGaAs film.
    Type: Application
    Filed: February 24, 2006
    Publication date: March 1, 2007
    Applicant: FUJITSU LIMITED
    Inventors: Shinsuke Tanaka, Ken Morito
  • Patent number: 7158547
    Abstract: A wavelength tunable laser device includes: a pair of reflection mirrors; a semiconductor element disposed between the pair of reflection mirrors, the semiconductor element integrating a region for providing an optical gain, a region having a wavelength tunable filter function and a phase control region; and an optical filter disposed between the semiconductor element and one of the pair of reflection mirrors, the optical filter having periodical transmission wavelengths. A wavelength tunable laser device is provided which is easy to be controlled and can be made compact.
    Type: Grant
    Filed: December 7, 2004
    Date of Patent: January 2, 2007
    Assignee: Fujitsu Limited
    Inventors: Shinsuke Tanaka, Ken Morito, Kazumasa Takabayashi